when (not exists(select * from table1 where id=1)) then into table1 select 1 as id, 'a' as data from dual; - 再比如以下的代码 if not exists(select * from table1 where id=2) insert into table1 values(2,'b') else update table1 set data='b' where id=2; 可以改写成 merge i...
通常我们使用if(exists(select ...)update...else insert,这样进行两遍表扫描,效率很低,在Oracle 9i以上有一个关键字merge,我们使用它就可以了。merge into 需要两个标操作,我们利用dual merge into referer_stat L using (select '1' from dual) N on (L.webid=234) WHEN MATCHED THEN UPDATE set count...
if not exists(select * from table1 where id=2)insert into table1 values(2,'b')else update table1 set data='b' where id=2;可以改写成 merge into table1 his using (select 2 as id, 'b' as data from dual) srcon (his.id=src.id)when matched thenupdate set his.data=sr...
通常我们使用if(exists(select ...)update...else insert,这样进行两遍表扫描,效率很低,在Oracle 9i以上有一个关键字merge,我们使用它就可以了。merge into 需要两个标操作,我们利用dual merge into referer_stat L using (select '1' from dual) N on (L.webid=234) WHEN MATCHED THEN UPDATE set count...
如果不存在insert ELSE IF update ELSE IF EXISTS并且不是数字DELETE From WHERE Insert或update on table违反外键约束(错误) 如何为这个查询写Insert、ignore或update? insert或update期间列上的Postgres和数学 Postgres:如果列在INSERT或UPDATE satement中,则从触发器引发异常 ...
user01: SQL> grant select, update, insert on product to user02; SQL> grant all on product to user02; user02: SQL> select * from user01.product; // 此时user02查user_tables,不包括user01.product这个表,但如果查all_tables则可以查到,因为他可以访问。 将表的操作权限授予全体用户: SQL> grant...
3) 两表(多表)关联update -- 被修改值由另一个表运算而来 update customers a -- 使用别名 set city_name=(select b.city_name from tmp_cust_city b where b.customer_id=a.customer_id) where exists (select 1 from tmp_cust_city b
UPDATEwarehouses wSETwarehouse_name = warehouse_name ||', USA'WHEREEXISTS(SELECT1FROMlocationsWHEREcountry_id ='US'ANDlocation_id = w.location_id );Code language:SQL (Structured Query Language)(sql) For each warehouse, the subquery checks whether its location is in the US or not. If yes,...
when matched then update set b = b+1;end ups;/drop table mergetest;create table mergetest(a ...
Feature2 :Include Query、Insert、Delete and Update //query by navvarlist=db.Queryable<Test>() .Includes(x => x.Provinces,x=>x.Citys ,x=>x.Street)//multi-level.Includes(x => x.ClassInfo) .ToList();//insert by navdb.InsertNav(list)//Finer operation than EFCore's SaveChange.Inclu...